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The 166.6 MHz radio frequency (RF) system with five superconducting HOM damped cavities is adopted to accelerate the 200 mA electron beam in the storage ring of the High Energy Photon Source (HEPS). The 166.6 MHz cavity cryomodules have been designed, constructed and horizontal tested at IHEP since the beginning of 2019. The thermal performances of the cryomodule are analyzed by numerical simulations which take into account the main contributors to the static heat loads at various temperature levels. The experiment investigations including the cool down, operating with RF power and static heat load measurements of the cryomodule are performed in the liquid helium cryogenic system. The calculated static heat loads have been compared with the experimental measurements, and the results show that deviations between the calculated heat loads and available experimental measurements at 4.2 K temperature level are within a small range, which indicates that thermal simulations are accurate. The detailed operating parameters in the cryogenic environment are reported. [ABSTRACT FROM AUTHOR]

Highlights • A new type of cryomodule for ADS Injector II is been presented. • Unique thermal design and performance of this taper cavity cryomodule are shown in this paper. • Some specific design effectively improves the commissioning performance of this cryomodule. Abstract A β = 0.15 taper cavity cryomodule has been designed for China Accelerator Driven Sub-critical System Injector II (ADS) at the Institute of Modern Physics (IMP) of the Chinese Academy of Science (CAS). And ADS Injector II linac has accelerated 10 mA proton beam to 25 MeV in June of 2017. This cryomodule is the third cryomodule of ADS linac and contains five β = 0.15 taper cavities and five 5.5 T solenoids operating at 4.2 K&1.05 Bar. First cool-down of this cryomodule was completed at the beginning of May in 2017. This paper will report the thermal design and performance of this taper cavity cryomodule. [ABSTRACT FROM AUTHOR]

Abstract A β = 0. 15 taper cavity cryomodule was designed for the China Accelerator Driven Sub-critical System Injector II(ADS) at the Institute of Modern Physics (IMP) of the Chinese Academy of Science (CAS). This cryomodule is the third cryomodule of the ADS Linac and contains five β = 0. 15 taper cavities and five 5.5 T solenoids that operate at 4.2 K and 1.05 Bar. Manufacturing of the cryomodule and construction of the cold mass was finished at the beginning of 2017. The cryomodule assembly was completed at the end of March, 2017. The ADS Injector II linac accelerated a 10 mA proton beam to 25 MeV in June of 2017. This paper reports the design, fabrication and performance of this taper cavity cryomodule. [ABSTRACT FROM AUTHOR]

We have developed a method to obtain mechanical centers of nine cell superconducting radio frequency (SRF) cavities from localized dipole modes, that is one of the higher order modes (HOM) induced by low-energy beams. It is to be noted that low-energy beams, which are used as alignment probes, are easy to bend in fringe fields of accelerator cavities. The estimation of the beam passing orbit is important because only information about the beam positions measured by beam position monitors outside the cavities is available. In this case, the alignment information about the cavities can be obtained by optimizing the parameters of the acceleration components over the beam orbit simulation to consistently represent the position of the beam position monitors measured at every beam sweep. We discuss details of the orbit estimation method, and estimate the mechanical center of the localized modes through experiments performed at the STF accelerator. The mechanical center is determined as x , y = ( 0 . 44 ± 0 . 56 mm , − 1 . 95 ± 0 . 40 mm ) . We also discuss the error and the applicable range of this method. [ABSTRACT FROM AUTHOR]

Conduction cooled current leads, which bring the current from the room temperature terminal down to the cryogenic environment, were used in common recently in large scale superconducting accelerators for its low cost, sample design and low heat load. In practice, the current lead is designed contained in a stainless steel tube. The heat load can be incepted in steps by thermal anchors, where one end is attached to the stainless steel tube, while the other end is connected with the cold shield of the cryomodule. Since the limitation of the welding technique, a thicker stainless steel tube needs to be used, and hence the thermal anchors cannot provide enough pressure to deform the tube enough to be in direct contact with the current lead, which may lead to temperature instability and bring extra heat load to the cryogenic system. An excellent option of epoxy filled current lead can realize the fully contact and reduce the heat load effectively. This paper will present the process of the current lead design, optimization, numerical simulation and cryogenic test, the test results show that the current lead can keep in a stable operation and low heat load. [ABSTRACT FROM AUTHOR]

The new LCLS-II Linear Superconducting Accelerator at SLAC needs superconducting magnet packages installed inside SCRF (superconducting radio frequency technology) cryomodules to focus and steer an electron beam. Two magnet prototypes were built and successfully tested at Fermilab. Magnets have an iron-dominated configuration, quadrupole and dipole NbTi superconducting coils, and splittable in the vertical plane configuration. Magnets inside the cryomodule are conductively cooled through pure Al heat sinks. Both magnets’ performance was verified by magnetic measurements at room temperature, and during cold tests in liquid helium. Test results including magnetic measurements are discussed. Special attention was given to the magnet performance at low currents where the iron yoke and the superconductor hysteresis effects have large influence. Both magnet prototypes were accepted for the installation in FNAL and JLAB prototype cryomodules [ABSTRACT FROM PUBLISHER]

A significant advance in magnetic field management in a fully assembled superconducting radiofrequency cryomodule has been achieved and is reported here. Demagnetization of the entire cryomodule after assembly is a crucial step toward the goal of average magnetic flux density less than 0.5 μT at the location of the superconducting radio frequency cavities. An explanation of the physics of demagnetization and experimental results are presented. [ABSTRACT FROM PUBLISHER]

The 1.3 GHz superconducting radio-frequency (SRF) technology is one of the key technologies for the ILC and future XFEL and ERL projects in China. With the aim to develop 1.3 GHz SRF technology, IHEP has started a program to build an SRF Accelerating Unit. This unit contains a 9-cell 1.3 GHz superconducting cavity, a short cryomodule, a high power input coupler, a tuner and a low level RF system. This program also includes the SRF laboratory upgrade, which will permit the unit to be built and tested at IHEP. The unit will be used for the 1.3 GHz SRF system integration study, high power horizontal test and possible beam test in the future. In this paper, we report the recent R&D status of this program. The first large grain low-loss shape 9-cell superconducting RF cavity made by IHEP reached 20 MV/m in the first vertical test in July, 2010. The prototype tuner and low level RF (LLRF) system are under test. The high power input coupler and cryomodule are under fabrication. Several key SRF facilities for 9-cell cavity surface treatment and pre-tuning were successfully commissioned and are in operation. [ABSTRACT FROM AUTHOR]

The high energy sections of the Fermilab HINS R&D proton linac will utilize superconducting spoke resonator (SSR) RF cavities. These will be assembled into cryomodules with strong solenoid focusing lenses closely interleaved with the cavities. A design for lenses has been made for the lower (SSR1) and higher (SSR2) energy ranges of the SSR-section. Prototype lenses for both SSR1 and SSR2 sections have been built and the SSR1 has been tested. Shielding is needed to reduce the solenoid fringe field on the cavity wall below the 10 \muT level, and a preliminary design was built and tested with the SSR1 prototype lens. We discuss the design requirements and challenges, and the results from quench testing and magnetic measurements of the SSR1 prototype lens. [ABSTRACT FROM AUTHOR]

In order to obtain the design, manufacture and operation experiences on the Superconducting Radio Frequency (SRF) cryomodule for the International Linear Collider (ILC), a test cryomodule for 1.3 GHz single 9-cell SC cavity was designed by IHEP (Institute of High Energy Physics) and TIPC (Technical Institute of Physics and Chemistry) jointly. This cryomodule will be used as a horizontal test facility for a 1.3 GHz 9-cell SC cavity. The cryogenic system for the cryomodule was also designed, which will be operated at 2.0 K with saturated superfluid helium. The major requirements, design, simulation results of the cryomodule are reported in the paper. This key component of a superconducting accelerator test unit will be built in the near future at IHEP. [ABSTRACT FROM AUTHOR]

Abstract: The Inter-University Accelerator Center, New Delhi is involved in commissioning a superconducting linear accelerator (LINAC) as a booster to its existing 15 UD Pelletron accelerator. The booster consists of three LINAC modules, each containing eight superconducting Nb quarter wave resonators and a superconducting solenoid magnet. The first LINAC module preceded by a superbuncher with one cavity and followed by a rebuncher cryostat with two cavities was installed in 0° beam line of Pelletron and has been under operation for some time at the Center. The module is integrated with a liquid helium (LHe) refrigerator through a cryogen valve box and the distribution line. The performance tests of each component like the RF cavity, the cryomodule and the liquid helium distribution line were carried out independently prior to the beam acceleration test. After having many trial runs on this integrated cryonetwork system, beam acceleration tests were performed during 2007. The energy of silicon beam with charge state of +10 has been enhanced approximately from 130MeV to 158MeV using the first module with seven effective cavities and the accelerated beam was delivered at user’s scattering chamber. The present paper highlights the performance of the first module producing an accelerating beam duly bunched in the rebuncher. The performance of first LINAC cryomodule along with problems and the solution associated with the cryogenic system and the cavities encountered during the beam runs are presented in this paper. [Copyright &y& Elsevier]

Abstract: This paper presents results of the photocathode cooling system test of the cell SRF gun at the Forschungszentrum Rossendorf. The SRF gun will produce short electron pulses with high bunch charges and low transverse emittance. The requirement for the superconducting electron linear accelerator in Rossendorf (ELBE) is to provide a low emittance electron beam up to 1mA current and 9.5MeV energy. Additionally, it will easily operate in continuous wave (cw) mode because of the low RF power losses in the superconducting material. Therefore, the normal conducting copper cathode must be cooled by liquid nitrogen in order to preserve the temperature of the cavity at 2.2K. The estimated power input from the RF field into the cathode could be more than 10W [P. vom Stein, Thesis, TU-Dresden, 1998]. First results of temperature measurements of the photocathode, respectively, from the cooling system at a heat load up to 30W are presented. [Copyright &y& Elsevier]

Abstract: SPIRAL2 is a radioactive beams facility, composed of a superconducting linac driver, delivering deuterons with an energy of up to 40MeV (5mA) and heavy ions with an energy of 14.5MeV/u (1mA). This facility is now fully approved by the French government. The first prototype of beta 0.12 quarter-wave resonator has been recently fabricated by Zanon company and tested at IPN Orsay. The details on its fabrication and the results of the RF and mechanical tests at 4K will be presented. Then, we will show the design of the cryomodule-B, dedicated to the high energy section of the linac, which is now ready to be ordered. Finally, the last studies of the R&D program, such as the last optimizations of the geometry, the new developments of the tuning system and the design of the helium vessel, are described. [Copyright &y& Elsevier]

Abstract: A heavy ion superconducting linac is being installed at TRIUMF to increase the final energy of radioactive beams from ISAC. A first stage of 20MV consisting of five medium beta cryomodules each with four quarter wave bulk niobium cavities and a superconducting solenoid is being installed with commissioning scheduled for December 2005. The cavities have been fully characterized for rf performance. Two cryomodules have been tested at cold temperatures. A high beta cavity (β 0 =0.104) for the next phase is presently in design. A weak phase lock loop technique is used to monitor the control loop phase noise to characterize system microphonics. A recent highlight is the acceleration of heavy ions by one cryomodule as a proof of system integrity. The report will summarize all aspects of the program. [Copyright &y& Elsevier]

Abstract: For the ELBE electron linear accelerator a superconducting accelerating module was developed and is now in routine operation. The cryostat contains two TESLA cavities (1.3GHz) and is designed for continuous-wave (CW) operation with an accelerating gradient of 10MV/m and a maximum average beam current of 1mA. For the RF power two 10kW klystrons are used. Special tuners, power couplers, low-level RF control, cryogenic control systems and safety systems were developed. Engineering design, operation parameters and experience with the module are discussed. [Copyright &y& Elsevier]